City looked to be heading out of the competition after Alfie May put fourth-tier Cheltenham ahead. But Foden equalised in the 81st minute before Gabriel Jesus and Ferran Torres struck to secure the team’s passage to the fifth round.
Guardiola’s side were without De Bruyne, who picked up a hamstring issue in Wednesday’s 2-0 Premier League win over Aston Villa. The Spanish manager said the impressive Foden has to focus on being the best version of himself.
“We have the players. Phil has to be Phil and not be Kevin De Bruyne because there is only one Kevin De Bruyne,” Guardiola, who expects to be without Belgian De Bruyne for up to six weeks, told reporters.
“He needs to keep doing what he has been doing in terms of when we are in a bad moment or when we are losing in terms of what he gave to the game. Phil is in a great moment and with great confidence. He’s clinical in front of goal.
“Phil can play in the middle, can play winger, can play in a false nine position up front. He’s playing really well, again in the right moment he scored a goal.”
City meet Swansea in the fifth round of the competition next month. They face West Bromwich Albion in the Premier League on Tuesday and can go top of the standings with a win.